Go here and download the March 1952 edition of Practical Mechanics (and any others that take you fancy). It was also published in one of the (two) Practical Mechanics How to Make it Books.

One was shown at the midland mex a few years ago, and it was I think on The tube. Dubious engineering then add harmonograph might find it. Noel.

A useful historical discussion /instructions here;

1920-1930.com.. ..Things To Make.. ..Harmonographs..

I can remember making harmonographs at school to show off on an open day (an awful lot of years ago). Made two different versions, one with two pendulums and one with a compound pendulum. The twin pendulum version had a wooden frame, basically a plank with two square holes in. Tthe pendulums were simply steel rod about 3/8" dia 30" below the pivot and about 6" above. The pivots were fabricated from steel bar and rod to form a collar which clamped to the pendulum rod by a bolt in a tapped hole. The pivots were knife edges located in a groove made as i recall by simply filing the edge of a steel bar and a groove cut on a shaper. the bar was brazed onto the collar before drilling the centre hole through the collar and bar. Large lumps of 2" rod were drilled through for the weights again just a tapped hole for a bolt to allow adjustment up and down the rod. The fixed side of the pivot was fixed to a plate which fitted to the frame.

One of the pendulums carried a table fixed to the top and the other a rod to hold the pen suitably counterbalanced. The pendulum with the table swung fore and aft whilst the pendulum with the pen swung left and right. By suitably adjusting the weight up and down different swing periods could be set up.

The single compound pendulum worked much the same but with a shorter main pendulum with another bob on a short rod suspended at the end of the main pendulam rod by means of a short length of fine chain. The arm with the pen was fixed to the table and just pivoted up and down.

Both machines worked quite well as I recall and produced a suitable selection of Lissajous figures duly affixed to the classroom wall. All good fun and I might even have learned something from the exercise. I least I can still remember the basics after nearly 60 years.

John

P.S. Saw a harmonograph being demonstrated at The Midlands Show in 2018

Found a link to a Video of the one at Midlands *** LINK ***

Edited By Journeyman on 31/07/2023 09:46:59

Edited By Journeyman on 31/07/2023 09:49:40

Couple of points.
Make the weights out of water bottles so that there is less bulk to move and store and adding a variable.
Don't make the bearings too low friction so they just go on for ever. Children will want things to come to an end fairly quickly.

Hi, there were a couple of designs in the 9/10 set and supermodels leaflets associated with Meccano in the 40's/ 50's.

These may be available on line

Ed

Here's an old book, available online.

"Harmonic Vibrations and Vibration Figures" by Joseph Goold. 1884.

https://archive.org/details/dli.ministry.13780/mode/2up

or… Internet Archive link

Edited By Tendor on 01/08/2023 06:58:08